1. Field of the Invention
This invention relates generally to lock devices for preventing rotation of nuts and bolts, and more particularly to an anti-rotation clip that removably engages a polygonal nut or bolt head and the curved exterior of a flange to prevent its rotation and facilitate tightening or loosening of the nut or bolt and eliminate the need to use two wrenches for tightening or loosening a nut or bolt.
2. Brief Description of the Prior Art
In a conventional studded flange connection a plurality of studs having threaded ends extend through the bolt holes of the mating flanges and nuts are threadedly engaged on the threaded ends of the studs. In conventional bolted flange connections a plurality of bolts extend through the bolt holes of the mating flanges and have nuts threadedly engaged on the end opposite the bolt heads.
Installing and removing the nuts and bolts from flanged connections is often difficult, particularly if the flanged connections have been exposed to harsh weather or corrosive elements, such as in oilfields, refineries, and chemical plants. In nearly all situations, it is necessary to use one wrench to hold the nut or bolt head on one side of the connection to prevent it from rotating while applying torque to the nut or bolt head on the opposed side of the connection. It is sometimes difficlut for one person to hold both wrenches and apply sufficient torque with one hand to tighten or loosen the connection.
In the case of flanged connections that been exposed to harsh weather or corrosive elements, such as in oilfields, refineries, and chemical plants, it is common to employ two persons for tightening and loosening the connection. One person holds a wrench to retain the nut or bolt head on one side of the connection to prevent it from rotating while the other person applies torque to the nut or bolt head on the opposed side of the connection with the second wrench. This procedure is time consuming and labor intensive, particularly in oilfields, refineries, and chemical plants, where there may be hundreds of flanged connections to assembled or disassembled.
There are several patents which disclose various devices for locking a nut or bolt to prevent rotation or preventing relative rotation between fastener elements, none of which engage the outer circumference of an associated flange.
Steele et al, U.S. Pat. No. 4,329,097 discloses a pair of nut locking cups that engage the external surfaces of a pair of nuts and have an outside radius equal to one-half of the distances between adjacent studs with a locking bar welded to the cups and between adjacent studs.
Gallagher et al, U.S. Pat. No. 4,735,533 and Linderman et al, Design U.S. Pat. No. Des. 305,927 disclose a locking assembly for locking a nut to a valve body which utilizes a lock plate with a peripheral depending skirt having an opening which surrounds the nut-like portion of a valve bonnet and has a slot spaced from the opening which receives a set screw and a nut to secure the lock plate to the valve body.
Mikel et al, U.S. Pat. No. 5,049,117 and Martin et al, U.S. Pat. No. 5,415,509 disclose an adjustable locking plate with a rectangular central aperture defined by upwardly bent straps and opposed arcuate end edges and opposed arcuate slots which receive bolts.
Puskas, U.S. Pat. No. 5,429,465 discloses a retainer structure for preventing relative rotation between a plurality of spaced apart nut-like fasteners utilizing a plurality of apertured plates each having a central polygonal aperture which is placed on a nut-like fastener and having opposed ends that are cut out to surround one-half of the adjacent nut-like fastener.
The present invention is distinguished over the prior art in general, and these patents in particular by a generally L-shaped anti-rotation clip for preventing rotation of a nut-like member (nut or bolt head) of a flanged connection to facilitate tightening or loosening of the nut-like member and eliminate the need to use two wrenches for tightening or loosening a nut or bolt. The clip has a horizontal portion and a vertical portion at one end thereof extending generally perpendicular thereto. A polygonal opening extending vertically through the horizontal portion has a plurality of discrete angled sides configured to surround and engage the sides of the nut-like member. The inner surface of the vertical portion is spaced a distance from the opening and is received on the outer surface of a flange with which the nut-like member is associated to prevent rotation of the surrounded nut-like member while torque is applied to a vertically opposed bolt head or nut connected with the surrounded nut-like member such that the nut-like member is prevented from rotating as torque is continued to tighten or loosen the connected nut-like member relative to the opposed bolt head or nut.